Wire-drawing die



June 4, 1935.

R. C. SHIPP WIRE DRAWING DIE Filed July 21, 1952 VENTOR C 5H/PP BY )f7 y@y ATTORNEY lso @attentati June i9 i935 cargar orgies ti/lllltlE-DRVHNGlllllllE Robert C. Shinn, East Urange, N. il., assigner to WestinghouseLamp Company, a corporationoli Pennsylvania Application `luly 2l, i932,Serial No. 623,69@

7 Claims.

This invention relates to improvements in the mountings of wire-drawingdies and relates particularly to dies for drawing tungsten filament wirefor incandescent electric lamps.

Dies of the character referred to herein as wire-drawing dies, consistof a body of hardened material or a naturally hard body such as adiamond having a hole formed therein with tapered approaching surfacesand a wire to be reduced in diameter is forced through the opening anddrawn to the size thereof.

Inasmuch as wire-drawing dies are employed under conditions where longservice is required and are subjected to relatively rough usage, undervariations in temperature conditions, they must be held in a rm andpermanent manner.

Heretofore, in mounting a diamond die, the diamond was held in a mountby surrounding the diamond with melted metal, such as copper or brass,or by spinning a flange of metal about the diamond. The use of amoldable material pre sented certain disadvantages in that during use,when the mount was subjected to heat, the diamond became loosened. Thiswas also true when a. die was held by spun metal. Consequently, theproduct, such as the wire being drawn, was damaged or the diameter ofthe wire variedcwing to the play between the mount and the diamond die.

The detrimental results attending the wiredrawing operation were causedby the expansion or contraction of the moldable material whichconstituted an enclosing body. When subjected to heat, as is necessaryin connection with tungsten and molybdenum wire-drawing, the surroundingmaterial in which the diamond was embedded wculd expand, resulting in acertain amount of compression which would be transierred along thesurface of the die so that when the die was cooled and the materialholding the die contracted, the tendency would be to loosen the die andpermit a small amount of play.

It has been found that when securing diamond dies by an enclosure ofmelted material, the direction ci movement of the material under hightemperature conditions is radial and a tendency is for the material tobreak' away from the diamond.

It is an object of the present invention to provide a diamond die heldinposition by a material capable of expansion in all directions tomaintain intimate contact with the die.

Another object oi the invention is to secure a wire-drawing die in acompact mass of material free from expansion or contraction detrimentalto the eective operation of the die.

Another object of the invention is to provide a medium for securing awire-drawing die in a mount so that the intimate contact between the dieand its supporting material is maintained under variations intemperature conditions.

Other objects and advantages will be evident from the followingdescription together with the accompanying drawing in which:

Figure 1 is a cross-sectional view of a die mount having a wire-drawingdie secured therein in accordance with the present invention;-

Figure 2`is a cross-sectional view showing a wire-drawing die positionedto be secured in a mount;

Figure 3 is a view partly in cross section showing a die positioned in amount ready to have an insert or plug applied to complete the mount;

Figure 4 is a view similar to Figure 3 but showing the plug in positionready to beground ofi; and

Figure 5 is a cross-sectional view of a wiredrawing die secured in amount in accordance with the present invention.

In accordance with the present invention, s. cementitous material suchas sodium silicate is employed as the medium for securing thewiredrawing die in position in a cavity of a mount. The material may bemixed with a suitable filler, such as kaolin, and then baked.

Figure 1 shows a die holder l@ in which a mount in is positioned. rI'hemount is provided with a cavity l2 and is in the form of a cup whichreceives an insert i3. A wire-drawing die tl is positioned so that itswire-drawing aperture l5 is in line with an aperture it in the mount andan aperture il in the insert. The aperture in the insert may be shapedafter the insert is in posi-4 tion in the cup.

The insert is so proportioned as to occupy the portion of the cavitybetween one side it of the die and the mount of the cavity. Around thedie is provided a filling of cementitious material it? which rnayconsist of kaolin and sodium silicate in the proportions as follows:

Kaoiin and sodium silicate in the proportions of i to 3 respectively byweight. Kaolin consti tutes the ller and may be any good grade of chinaclay and the sodium silicate usedniay be what is known in the trade asgrade E, specific gravity at 20 C. of not more than 1.40 nor less than1.36 and containing not more than 9.1% or not less than 8.9% NazO. Thiscommercial grade of sodium silicate is readily obtainable in the openmarket. The iiller and sodium silicate is mixed to provide a compositionin the form of a paste. The mount is then ready for use.

When completing a mount as shown in Figure l, the die, as shown inFigure 2, is so positioned as to lie on the bottom surface or" thecavity l2 with the wire-drawing aperture i5 of the die in alignment witha passage 2li in the mount. The

passage through the mount and the diamond may be aligned by means of acentering instrument 2l or by placing. the die so that a beans. ci lightcom-a ing up through the hole in the mounting or blank passes throughthe hole in the diamond.

-Next, the diamond supporting material i9, which is in a plasticcondition, is disposed around the die after which the insert i3, whichis provided with a hole i3 for the escape of air, is applied and forcedinto position by a force member 22. The insert or plug is positioned sothat it makes contact with the die.

When the insert is forced into the position, as shown in Figure 4, theportion 23 thereof may be ground oi after which the die is polished andfinished by shaping to form the tapered passages I6 and I1 which lead tothe wire-drawing aperture of the die. The hole is then cleaned of anyexcess material and the mount is heated to about 400 C. This baking-converts the paste to a hardened mass which expands slightly and lls upany voids that may be present.

In the manufacture of ne wire such as is used for the filaments forelectric incandescent lamps, for example, it is necessary to draw wiresuch as tungsten to very fine diameters, as for example, from 1 to 10mils. It has been found that a die held by a mass of cementitiousmaterial, as above set forth, meets operating requirements for suchsizes satisfactorily. When larger diameters are desired it has beenfound an advantage to strengthen the holding material by adding metallicpowder such as copper, brass or the like with a small amount of zinc.The metallic powder may be substituted for the filler and a tenaciousand durable setting for the die is obtained. When using a metallicpowder in combination with sodium silicate as a binding agent, sodiumsilicate is added to the metallic powder until it has the consistency ofa thick paste so as to be conveniently handled.

The paste is easily applied by pressing about the positioned diamond inthe bottom of the cupl of the mount after which the insert or plug isforced into position and the baking operation is performed.

It has been found in practice that the use of sodium silicate as aholding medium for dies avoids previous disadvantages and that the diedoes not change its position when subjected to the temperaturesattending the drawing operation and a tight bond is maintained between.the die and the holding medium.

'I'he use of a powdered metal has the advantage of allowing freeexpansion and contraction of the particles when subjected to temperaturevariations and, by reason of the strength of this holding medium, wireof from i to, 2i! mils or above may be drawn.

The present construction of die mount diifers from that heretoforeemployed in that the mount as described includes, in addition to the cupfor holding the wire-drawing die, the insert or plug which,` asexplained, is forced into the cup and occupies the portion thereof notoccupied by the die and the cementitious or holding medium. The insertis proportioned to have a tight t with the interior cylindrical wall ofthe cup and, therefore, serves as a 4protective wall for the materialwhich holds the die. By reason ofthe insert or closure for the cup, thedie and the layer of material in which it is embedded is effectivelyremoved from the direct heat during the Wire-drawing operation.

Furthermore, by reason of the insert, a relatively long taperedpassageway may be provided leading to the aperture in the Wire-drawingdie. A mount, therefore, constructed in accordance with the presentinvention, is provided with a material which not only serves to rigidlyand securely support the die, but the mount itself, by reason of theinsert, provides means for protecting the die as well as the holdingmedium.

It has further been found that when using dies surrounded by meltedmetal the lack of intimate contact between the die and the metal limitsthe use of the die to the drawing of wire through a relatively smallrange of diameters and if, such a die were used to draw Wire atrelatively large diameters, the drawing operation would exert a.pressure greater than the die would ordinarily stand causing it tocrack, particularly when using a diamond die. For example, if a diamondwere selected to draw wire of one to two mils such a diamond ordinarilywould not stand drawing wire of ten mils.

By reason of the present invention, wherein the die is supported by themetallic particles, a sufficient opposing force is present to permit adiamond die to draw wire, as above mentioned, of from one to 20 mils.This is of considerable advantage from a manufacturing and cost stand4point since it means that, whereas heretofore a 1/6 or 1A. karat diamondwas used to draw one mil wire, it was necessary to use a one-half karatdiamond to draw ten to 20 mil wire. In the present case, and by reasonof the supporting medium for the diamond, the diamond will take care oflarge sizes.

Although a preferred embodiment of the invention is shown and describedherein, it is to be understood that modifications may be madeI thereinwithout departing from the spirit and scope of the invention as setforth in the appended claims.

What is claimed is:

l. A mount for a wire-drawing die comprising a. cup, a wire-drawing diedisposed on the bottom of the cup and embedded in a mass of sodiumsilicate.

2. A mount for a wire-drawing die comprising a cup, a layer of a mixtureof baked sodium silicate and a filler in the bottom of said cup and adie embedded in said layer.

3. A mount for a wire-drawing die comprising a cup, a layer of a mixtureof baked sodium silicate, a ller in the bottom of said cup and ametallic closure for said cup.

4. -A mount for a wire-drawing die comprising a cup, a layer ofdehydrated sodium silicate and a metallic powder in the bottom of saidcup and a die embedded in said layer.

5. A mount for a wire-drawing die comprising a cup, a layer ofdehydrated sodium silicate and a metallic powder in the bottom of saidcup, a die embedded in said layer and a metallic closure for said cup.

6. A mount for a wire-drawing die comprising a cup, a wire-drawing diedisposed on the bottom of the cup and imbedded in a mass of sodiumsilicate and a metallic closure for said cup.

7. A mount for a wire-drawing die comprising a cup, a die disposed atthe bottom of said cup,

and imbedded in an adhesive composition comprised of separate metallicparticles free to expand and contractA in all directions for holdingsaid die in position in said cup.

ROBERT C. sHrPP.

